The invention relates to a substructure for structures, particularly for sport fields in trough-shaped support frames or for stand sections which, by means of vertical support arranged underneath and equipped with rollers or sliding cushions, are horizontally movable by rolling or sliding on tracks embedded in a sub-floor.
The scarcity and high cost of building land, as well as current maintenance costs force stadium operators to search for the possibility of using a soccer field and/or a light-athletics stadium more than once a week or once in 14 days. In order to arrange big events, such as certain concerts, stages must be erected in the stadium. During the construction and dismantling of the stage, and also partially due to the big event itself, immediate damage to the grass can not be avoided, even when the stadium grass is covered by plates or the like.
Moreover covered multi-purpose halls can be used for various sports, as well as for concerts, shows or the like by functionally restructuring their interior spaces. However as a rule the hall interior is too small for soccer, rugby or light-athletic throwing sports. But even a multipurpose hall with correspondingly large dimensions would be inappropriate for an interior requiring a durable grass surface, since in the closed halls it would lack the natural growth conditions such as sufficient sun light and watering by rain. These conditions can be only partially fulfilled by an unfolding or sliding roof. In any case the drawback of considerable damage to the grass due to the multiple use persists, so that after only a short time it will no longer suit the requirements. The substitute use of rolls of natural lawn is excluded, since the respective lawn strips or lawn squares do not have enough time to firmly bond with the substrate.
Besides, the requirements for sports stadiums and concert or show arenas are completely different. While in the case of sports stadiums the problem is to create space for as many spectators as possible around the sport field, which is rectangular, such as for soccer, or oblong/oval such as for light-athletic events, in the case of a show or a concert the spectator space behind the stage is not needed or cannot be used at all, so that otherwise usable spectator rows can go unused.
Therefore multifunctional arenas have been proposed, wherein sports and show spaces can be shifted in relation to the spectator rows. The respective sports field rests then, e.g. as described in GB 2 263 644 A, on one or more supports which on the upper side carry the grass and an underlying soil substructure, and which is slidable along slide or roller tracks in relation to a base. The same applies for such supports which carry ice-hockey fields, elastic wood floors or the like. By displacing these supports the desired play field or any other support construction can be brought to the center of the arena or removed from there.
In FR 2 441 033 A1 it has been proposed to arrange not only individual playing field sections so as to be horizontally slidable, but also to make sections of the stands shiftable. However the method described therein, which lets the respective sections xe2x80x9cfloatxe2x80x9d has proven unsuitable in practice. By contrast slide cushions made of polytetrafluoroethylene (PTFE) on steel tracks have proven themselves in practice. The required horizontal propelling force is provided by means of hydraulic cylinders.
In all cases there are problems during inspections and repair work, namely in the area of the underside of the support frame, or of the support located there, and particularly in the rollers or slide cushions, which for the horizontal displacement of the heavy load of support frames or stand sections are subject to heavy wear during use and have to be replaced. The space available underneath a support frame or a stand section is as a rule too shallow, so that underneath this construction an inspection space or passage must be provided, which makes possible inspection, as well as repair. Furthermore it must be possible to effect repair and replacement of the respective slide cushions, rollers, supports, etc.
It is therefore the object of the present invention to provide an improved substructure for the purposes described, particularly with respect to inspection passages, for easy repair and if necessary replacement of the existing roll or sliding means, or other structural components located therebelow.
This object is achieved in substructure particularly for sport fields in trough-like support frames or for stand sections which are supported on and horizontally slid or rolled on tracks embedded in a sub-floor by means of vertical supports arranged underneath and provided with rollers or slide cushions according to the invention, by means of one or more raisable bridges, which can be lifted by hydraulic cylinders supported on foundations or on pile heads. Preferably on the underside of the support frames or on the upper side of the bridges, supports are provided which can consist for instance of PTFE cushions. The maximal stroke of the hydraulic cylinder transmitted to the bridge has to be bigger than the range of inherent elasticity of the rollers or slide cushions under load. Only when this condition is fulfilled will the slide cushions or rollers lift from the respective tracks and can be inspected. If according to a preferred further embodiment of the invention, underneath the bridge a passable inspection space is arranged, then the accessibility of the slide cushions or rollers (from underneath) is considerably facilitated.
As an alternative to the aforementioned solutions, it is also possible to provide additional supports against which or from which hydraulic cylinders can be vertically advanced, which are supported either on platforms or on pile heads or on a track bridge arranged between two track ends. In this variant the substructure with its additional supports is oriented through horizontal displacement so that it can be lifted by the hydraulic cylinders, so that respective rolling or sliding means required for the horizontal displacement can be relieved. Preferably under the track bridge a movable inspection space is arranged.
The accessible inspection space is the equivalent of a separation of the sub-floor from the rail or slide system. In the inspection passage the length extension of the slide tracks or rails cannot be embedded in the sub-floor, but have to be compensated for. For this purpose preferably the track of the track bridge has two mutually facing track end pieces, and the gap located between them can be closed by a horizontally movable wedge, whose wedge surfaces can be each applied under pressure substantially with a positive lock to the respective and surface of the respective track end piece in a common application plane. The two track ends of the track bridge are provided to be freely movable in the track direction, whereby the nominal distance between the two track ends can be changed. Through corresponding insertions and retractions of the wedge, the distance between the two track ends can be completely filled up. The wedge shape also insures that a compensation of the length extension of the slide or roll track is possible. In order to insure that the wedge is kept in the intended place even during the passage of a slide cushion or roller, the wedge is preferably hydraulically actuatable. In particular the wedge covers an opening to the inspection space. The aforedescribed variant creates the possibility that the support frame or the stand section can be lifted at least in the region of the inspection passage, so that through the opening covered by the wedge, after the retraction of the wedge, a slide bearing or a roller no longer under load is also accessible from the inspection space. Through such an inspection passage it is possible to inspect, repair or replace each slide cushion or roller, by successively moving the support frame of the stand section.